Untitled

#include <bits/stdc++.h>
using namespace std;

#define int long long
void __print(int x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned int x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V> void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x)
    cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cerr << ", ";
  _print(v...);
}
#ifndef ONLINE_JUDGE
#define debug(x...)                                                            \
  cerr << "[" << #x << "] = [";                                                \
  _print(x)
#else
#define debug(x...)
#endif

void solve() {
  int n;
  cin >> n ;
  string a;
  string b;
  cin >> a >> b;
  string temp = b;
  reverse(temp.begin(), temp.end());
  string c = temp;

  //normal 
  int count1= 0;
  for(int i=0;i<n;i++){
    if(a[i]!=b[i]){
      count1++;
    } 
  }
  if(count1 == 0 ){
    cout<<0<<endl;
    return;
  }
  if(count1 == 1){
    cout<<1<<endl;
    return;
  }
  int ans1= count1*2-1;
  debug(count1,ans1);

  //reverse
  int count2 = 0;
  for(int i=0;i<n;i++){
    if(a[i]!=c[i]){
      count2++;
    }
  }
  //oyoyoy
  //yoyoyo
  //yoyoyo

  int ans2 = count2*2;
  debug(count2,ans2);
  if(count2 ==0){
    ans2 = 2;
    cout << ans2 << endl;
    return;
  }
  cout<<min(ans1,ans2)<<endl;

  // abcdefgh
  // hbfduegh
}

signed main() {
  int t = 1;
  cin >> t;
  while (t--) {
    debug(t);
    solve();
  }

  return 0;
}